Cataract surgery generally involves the removal of the natural lens and the implantation of an intraocular lens. Both extracapsular lens removal, which leaves the posterior capsule, and intracapsular removal in which the natural lens is removed, together with the lens capsule, require relatively large incisions in the eye of the order of 7 to 8 millimeters in length. Phacoemulsification, which breaks up the natural lens with ultrasound and removes the pieces, requires a small incision of only about 3 to 31/2 millimeters in length.
A small incision in the eye is greatly preferred because it produces less trauma, minimizes fluid losses, reduces the likelihood of infection and inflammation and minimizes and facilitates the suturing required to close the incision. Although phacoemulsification requires only a small incision for removal of the natural lens, the optic of the intraocular lens is typically of the order of 6 millimeters in diameter and, therefore, is too large to pass through the 3 to 31/2 millimeter incision. Accordingly, even if phacoemulsification is used, it is necessary to enlarge the incision in order to insert the intraocular lens.
In an effort to overcome this, it has been proposed in Kelman U.S. Pat. No. 4,451,938 to construct the intraocular lens in multiple pieces, insert the pieces separately into the eye and then assemble them within the eye. Unfortunately, the surgical techniques required for assembly of the individual pieces of intraocular lens in the eye are extremely difficult.
It has also been proposed in Mazzocco British Patent Application No. 2,144,315 and Kelman European Patent Application No. 83303414.3 to utilize a deformable optic which can be folded for insertion through a small incision into the eye. One problem with this approach is that it has been difficult to find materials which are both adequately deformable and suitable for use as an optic.